1. Field of the Invention
The present invention relates to a lamp for a vehicle. More specifically, the present invention relates to a lamp for vehicle such as a headlamp or a tail lamp with an improved design that can give a three-dimensional appearance to the light emission surface.
2. Background Art
A conventional lamp for vehicle having such a configuration is disclosed in Japanese Unexamined Patent Publication No. Hei 8-148006, for example, which was applied by the same applicant and was invented by the same inventors as the present invention. This lamp for a vehicle uses imaginary plane 10 shown in FIG. 1, to which a cross hatching pattern 11 is applied. The cross hatching pattern 11 consists of two crossing groups of plural lines that are disposed in parallel at a constant pitch. This imaginary plane 10 is deformed into a desired shape. Thus, a process surface 12 is formed, in which the pitch of the cross hatching pattern is changed in accordance with the deformed shape. A planar deformed cross hatching pattern 14 is obtained by orthographically projecting the pattern of the process surface 12 onto a lens surface 13. The lens surface is processed in accordance with the projected pattern. The processed lens surface 13 formed by the above-mentioned process gives an observer an optical illusion that it is deformed into the shape given to the process surface 12, so that a three-dimensional appearance is given to the lens surface 13.
However, in the above-mentioned lamp for vehicle discloses only the meaning for changing the pitch of the lens cut processed to the lens surface. Therefore, depending on the shape of the deformation, an excessive rate of difference can be generated among the pitch, so that the production of the lamp is difficult. In addition, it is possible that an expected effect of the three-dimension appearance cannot be obtained. Furthermore, the production of the mold may require much effort, so a partial modification is difficult. It is desired to solve these problems.